A driving support device that provides information of a traffic sign arranged at a road on which a vehicle travels is described in Patent Literatures 1 to 3, for example.
A device described in Patent Literature 1 recognizes a speed limit, on the basis of a traffic sign or a road marking included in a video of a scene ahead of a vehicle, which is imaged by a vehicle-mounted camera. Then, when a vehicle speed obtained from the vehicle exceeds the recognized speed limit, the device disclosed in Patent Literature 1 outputs an alarm.
A navigation system described in Patent Literature 2 estimates a road on which a vehicle travels, on the basis of a position of the vehicle detected by using a GPS (Global Positioning System) and road data which is stored in a road data storage means. The road data storage means also stores a speed limit of roads in addition to the data of the position of the roads. Then, the navigation system retrieves the speed limit on the road on which the vehicle is estimated to travel, from the road data storage means. When a speed outputted from a vehicle speed sensor exceeds the retrieved speed limit, the navigation system outputs an alarm.
A navigation device disclosed in Patent Literature 3 holds coordinates of a characteristic object, such as a building, separately for users. Then, the navigation device estimates a road on which a vehicle travels, on the basis of a current position of the vehicle obtained by using a GPS and map data. The navigation device determines whether the characteristic object is the right side or the left side relative to the road on which the vehicle travels in a traveling direction of the vehicle, on the basis of the coordinates of the characteristic object, the current position, and the traveling direction. When the vehicle approaches the characteristic object, the navigation device outputs a result of the determination.
Patent Literature 4 describes a map database updating system that updates a map database by using a result of checking of a type and a position of a traffic sign derived from a video of a camera mounted to a vehicle against a traffic sign over the map database. A navigation device included in the map database updating system recognizes the type of the traffic sign and a relative position relationship, such as a distance and a direction, of the traffic sign to the camera, on the basis of the video of the camera mounted to the vehicle. Then, the navigation device calculates the position of the traffic sign, on the basis of the relative position relationship of the traffic sign to the camera and a position and a direction of the vehicle measured by using a GPS, a sensor, and the like. When the calculated position of the traffic sign and contents included in the map database are different, the map database updating system changes the position of the traffic sign in the map database to the calculated position.